Head Restraints Static Height and Backset Measurement Hans Ammerlaan

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Head RestraintsStatic Height and Backset
MeasurementHans Ammerlaan
GTR7-02-15
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Content

• - Reasoning behind NL proposal for GTR7-01-03
• - Comparison erect sitting height dummies versus
  human males
• - Conclusions

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Reasoning behind NL proposal for GTR7-01-03

• Within EEVC the method of UNECE Reg.17 Head
  Restraint Measurement Method has been taken on
  board as part of a Cost-benefit Analysis
• The published report UK Cost-benefit
  Analysis Enhanced Geometric Requirements for
  Vehicle Head Restraints
• can be downloaded from www.eevc.org
• In its Appendix Regulation 17 Head Restraint
  Measurement Method it is explained by means of
  a series of five figures what serious errors can
  be made
• GTR7-01-03 shortly mentions this problem these
  figures are reproduced here to illustrate the
  problem

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Fig.1 UN-ECE Regulation 17 method for measuring
head restraint height
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Figure 2 NHTSA conversion between RCAR and
UN-ECE Reg. 17 head restraint height measurements
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Figure 3 Underestimation error in backset
conversion
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Figure 4 Effect of backset error on height
estimation
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Figure 5 Additional error arising through
inclined line defining the top of the head
restraint
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Erect sitting height dummies versus human males
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Erect sitting height dummies versus human males
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Conclusions (1)

• The goal of a head restraint with an appropriate
  height is not only reached through taking account
  of Anthropometry
• The present UNECE Reg.17 static height
  measurement method (which is also in gtr7) simply
  measures this height to the top of the head
  restraint, without relating this measurement to
  the fact whether this height is too far backwards
  or not
• So the present method could easily over-estimate
  the height that effectively is protecting people,
  because the top could mean the backmost corner of
  the head restraint (the total error of the shown
  seat is 48 mm)
• Therefore the NL doc. GTR7-01-03 proposes to link
  the following three measurements
• the measurement of head restraint height (above
  the R-point)
• the measurement of backset
• the measurement of the height of the front
  contact surface of the head restraint (measured
  on the median longitudinal plane) in order to
  provide an appropriate catching zone

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Conclusions (2)

• The option of using the 3-D-H machine equipped
  with the HRMD-probe (this combination should
  represent the UMTR mid-sized male, see
  UMTRI-83-53-1) causes difficulties
• Using a Coordinate Measuring Machine (in
  combination with a semi-spherical headform probe)
  will exclude non-biofidelic interaction caused by
  the 3-D-H machine, and can easily provide data
  with regard to the head restraint height in
  combination with its backset (values can be
  related to the R-point)
• The advantage of using the method with the
  Coordinate Measuring Machine is that also backset
  can be checked for people taller than a mid-sized
  male that originates from more than 25 years ago!

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Thank you for your attention